Various agricultural vehicles are configured to support a header for cutting, gathering, or otherwise processing crop material. For example, agricultural windrowers may be configured to support various headers configured to cut crop material from the ground and arrange the cut material in windrows for later processing (e.g., by a separate baler). As another example, agricultural combines may be configured to support various headers configured to cut crop material from the ground and move the cut material into the body of the combine for further processing (e.g., threshing and winnowing).
In order to raise, lower, and otherwise move or support an attached header, various agricultural machines (e.g., windrowers, combines, and so on) may include one or more hydraulic cylinders. For example, one or more cylinders may be provided for generally raising or lowering a header, one or more cylinders may be provided for tilting the header laterally, and one or more cylinders (e.g., in communication with one or more accumulators) may be provided to float the header with respect to the ground. In certain configurations, these cylinders may be included, respectively, in distinct hydraulic circuits or in distinct portions of a single hydraulic circuit.
In order to perform maintenance on a header, an operator may generally lower the header, such that the header is fully supported by the ground (or another support) rather than the agricultural vehicle. An attached header may also be lowered to the ground in order to replace that header with another (e.g., a header configured for different crops), or for various other reasons. Known hydraulic systems for lifting, floating or tilting the header, however, may tend to remain somewhat pressurized even when the header appears to have been fully lowered to the ground. This trapped pressure may result in undesirable movement, or resistance to movement, of the header or of other components of the vehicle during maintenance of the header (or other operations). For this reason, and others, it may therefore be useful to provide a system and method for appropriately relieving pressure within relevant hydraulic systems when a header is to be lowered (or in various other instances).